In the case of MOS devices, the progressive reductions in size of structure and the smaller oxide thicknesses that this entails at the gate terminals gives rise to the problem that the supply voltage for modern circuits has to be further and further reduced. Excessively high supply voltages can lead to damage or even destruction of MOS devices, due to the change in electrical properties. Voltage resistance or dielectric strength in terms of the drain-source contacts in so-called high-voltage MOS transistors is achieved substantially by low-doped drift regions. In order not to worsen the electrical properties of the MOS transistors however the oxide thickness cannot be increased just by any desired amount to improve dielectric strength. In order to be able to transmit a voltage signal with an MOS transistor as far as possible without any influence, having regard to the threshold voltage of the MOS transistor, for example in the case of an NMOS transistor, the magnitude of the gate potential must be greater than the drain or source potential. In the case of multiplexers or output switches however it is often necessary to switch voltages which are higher than the technologically maximum admissible gate-source voltage. The problem also arises in relation to cardiac pacemakers or defibrillators in which stimulation or defibrillation signals which embrace a large dynamic range have to be switched. In that case the maximum admissible gate-source voltage can be exceeded, and that can result in damage to or destruction of the transistor.
DE 37 88 876 T2 discloses a programmable cardiac pacemaker which has MOS switches controllable by logic members. The problem of being able to switch only signals with signal voltages within a limited voltage range when using MOS switches is not mentioned here and is also not resolved.